Well screen apparatus and method of manufacture

ABSTRACT

Disclosed is a well screen assembled on a base pipe and having an improved drainage layer disposed between the outer filter material and the base pipe. The improved drainage layer can be formed from a variety of materials and shapes. The drainage layer can be manufactured separately from the base pipe in the form of a tube severed along its length and subsequently assembled on the base pipe.

CROSS-REFERENCE TO RELATED APPLICATIONS

None

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None

REFERENCE TO MICROFICHE APPENDIX

Not applicable

TECHNICAL FIELD

The present inventions relate generally to subterranean mounted well screens used in the production equipment and processes of hydrocarbon wells to filter harmful solids from produced hydrocarbons and more particularly these inventions have particular aspects in well screens that provide support for the filter medium and form a drainage layer.

BACKGROUND OF THE INVENTIONS

The oil and gas industry utilized horizontal well drilling and completions as a more-efficient production method than producing hydrocarbons into vertical wellbores. Horizontal well sections thousands of meters long have been completed with well screens to filter out harmful solids from the produced hydrocarbon fluids.

Non-uniform production along the length of the well screens in the producing portion of the well can cause screen failure and resulting undesirable water production.

In heterogeneous or fractured formations, high permeability areas are encountered. Well screens in these areas can be prematurely damaged or plugged. Solids moving through the screen in these higher flow areas either cause premature erosion failure of the screen or quickly collect on the screen causing the screen to plug or fail by collapse against the base pipe. These screen failures contribute to additional unbalanced production.

In conventional and flow-controlling well screens, a filter medium (typically a screen) is mounted around a base pipe. A perforated metal shroud is commonly positioned around the entire assembly for protection. In conventional well screen assemblies, the base pipe is perforated or slotted, and, in flow-controlling well-screen assemblies, the base pipe is solid in the area adjacent to the filter medium. In both configurations, pressure drops across the filter medium can cause screen failures in the form of a radial inward collapse of the filter medium.

In some well-screen assemblies support structures are present between filter medium and base pipe to support the filter medium against collapse and to form a drainage layer. However, existing support structures for well screens, while providing support, are either complex, expensive to manufacture or for other reasons have not proven to be entirely satisfactory. Thus, there are needs for improved well-screen designs including improvements in filter medium support structures.

SUMMARY OF THE INVENTIONS

The present inventions provide improved subterranean well-screen apparatuses and methods of manufacture.

More specifically, the present inventions are directed to improved drainage layers for well screens.

In a further aspect, the present inventions are directed to improved well screens.

A more complete understanding of the present inventions and the advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section of a portion of a subterranean wellbore incorporating the improved well screens of the present inventions;

FIG. 2 is a sectional view of one exemplary embodiment of the improved well screen of the present inventions;

FIGS. 3 a and 3 b are sectional views of the well screen of FIG. 3 taken on line 3-3 looking in the direction of the arrows;

FIG. 4 is an isometric view of the drainage layer portion of the well screen of FIG. 2;

FIGS. 5 and 5 a illustrate an enlarged sectional view of the drainage layer of FIG. 4;

FIGS. 6 is a sectional view similar to FIG. 2 of another exemplary embodiment of the improved well screen of the present inventions;

FIG. 6 a is an isometric view of a tube from the FIG. 6 embodiment;

FIG. 7 is a sectional view similar to FIG. 2 of further exemplary embodiment of the improved well screen of the present inventions;

FIG. 8 is a sectional view similar to FIG. 2 of an additional exemplary embodiment of the improved well screen of the present inventions;

FIGS. 8 a and 8 b are isometric views of a channel from the FIG. 8 embodiment;

FIG. 9 is an isometric view of an alternative configuration of the channel suitable for use in the FIG. 8 embodiment;

FIG. 10 is a sectional view similar to FIG. 2 of a further exemplary embodiment of the improved well screen of the present inventions;

FIG. 10 a is an isometric view of the drainage layer structure of the FIG. 10 embodiment;

FIG. 11 is a sectional view similar to FIG. 2 of an additional exemplary embodiment of the improved well screen of the present inventions;

FIG. 11 a is an isometric view of the angle member of the FIG. 11 embodiment;

FIG. 12 is a sectional view similar to FIG. 2 of another exemplary embodiment of the improved well screen of the present inventions;

FIG. 13 is a sectional view similar to FIG. 2 of a further exemplary embodiment of the improved well screen of the present inventions; and

FIG. 14 is a quarter sectional view similar to FIGS. 3 a and 3 b of another exemplary embodiment of the improved well screen of the present inventions.

DETAILED DESCRIPTION

The present inventions provide improved well-screen apparatuses and methods of manufacture. It is to be understood that the various embodiments of the present inventions described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention. The embodiments are described merely as examples of useful applications of the principles of the invention, which is not limited to any specific details of these embodiments.

The term “vertical wellbore” is used herein to mean the portion of a wellbore to be completed which is substantially vertical or deviated from vertical in an amount up to about 15°. The term “horizontal wellbore” is used herein to mean the portion of a wellbore to be completed which is substantially horizontal, or at an angle from vertical, in the range of from about 75° to about 105°. All other angular positioning relates to a deviated or inclined wellbore.

Since the present inventions are applicable in horizontal and inclined wellbores, the terms “upper and lower” and “top and bottom” as used herein are relative terms and are intended to apply to the respective positions within a particular wellbore, while the term “levels” is meant to refer to respective spaced positions along the wellbore. In the following description of the representative embodiments of the invention, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. In general, “above”, “upper”, “upward” and similar terms refer to a direction toward the earth's surface along a wellbore, and “below”, “lower”, “downward” and similar terms refer to a direction away from the earth's surface along the wellbore.

Representatively illustrated in FIG. 1 is a well system 10 which embodies principles of the present inventions. A production tubing string 12 is installed in a wellbore 14 of a well. The tubing string 12 includes multiple well screens 16 positioned in an uncased generally horizontal portion of the wellbore 14.

One or more of the well screens 16 may be positioned in an isolated portion of the wellbore 14, for example, between packers 18 set in the wellbore. In addition, or alternatively, many of the well screens 16 could be positioned in a long, continuous portion of the wellbore 14, without packers isolating the wellbore between the screens.

Gravel packs could be provided about any or all of the well screens 16. If desired, a variety of additional well equipment (such as valves, sensors, pumps, control and actuation devices, etc.) could also be provided in the well system 10.

It should be clearly understood that the well system 10 is merely representative of one well system in which the principles of the inventions may be beneficially utilized. However, the inventions are not limited in any manner to the details of the well system 10 described herein. For example, the screen sections 16 could instead be positioned in a cased and perforated portion of a wellbore; the screen sections could be positioned in a generally vertical portion of a wellbore. The screen sections could be used in an injection well rather than in a production well, etc.

Referring now to FIGS. 2 and 3, enlarged schematic cross-sectional views of the screen section 16 are illustrated. The well screen 16 may be used in the well system 10, or it may be used in any other well system in keeping with the principles of the inventions. The well screen 16 is of the type that includes a flow control device to meter the fluid flowing into the production string from the string. It is to be understood that the present inventions apply to other types of well screens including those with perforations along the length of the base pipe and those without fluid flow control.

Screen section 16 comprises a base pipe 30, surrounded by a filter 32 and a perforated outer shroud 34. The base pipe and shroud are typically made from metallic materials such as steel but non-metallic materials can be sued. Fluids flow from the material surrounding the wellbore through the perforations in the shroud 34 and through the filter 32. The screen 16 functions to filter solids out of the fluids before they enter the base pipe.

The outer shroud 34 typically is a tubular member installed for protection. In some screen designs, the shroud is not present. The base pipe 30 is typically a tubular member thirty feet long with an internal axially-extending passageway that forms a flow path. The base pipe 30 acts as the backbone and provides structural stability to the screen section 16. Typically, the ends of the base pipe 30 are threaded (not shown) to allow the screen section 16 to be coupled into the production string system. Perforations, ports or slots are provided in the wall of the base pipe to allow flow into the interior. In some screen systems these openings in the wall are spaced along the length of the base pipe and in others, such as flow-control screens, the placement of the holes is localized. While the present inventions are not limited to flow-controlling screens, the exemplary embodiment selected for describing the present inventions as illustrated in FIGS. 2-3 is a flow-control type screen with openings or perforations 40 located only at one end of the base pipe 30.

The filter portion 32 is typically tubular shaped and is made from a filter medium such as wire wraps, mesh, sintered material, pre-packed granular material, and other materials known in the industry. The filter medium can be selected for the particular well environment to effectively filter out harmful solids from the hydrocarbon production.

A drainage layer 36 can be formed in the annular space 38 formed between the filter portion 32 and the outer surface of the base pipe 30. Fluids flow inwardly (or radially) through the filter portion 32 and into the drainage layer 36. The drainage layer 44 allows fluids in the annular space to flow parallel to the outer surface of the base pipe 30 in axial and circumferential directions.

The screen system 16 shown in FIGS. 3 a and 3 b is a flow control type screen assembly. In this embodiment the drainage layer 36 is blocked at one end (see FIG. 3 b) and, as shown in FIG. 3 a, communicates with an annular chamber 42 forming the input of a flow control assembly 44 (sometimes called an inflow control device). The flow-control assembly 44 is positioned between the fluid leaving the drainage layer 36 and the ports 40. Basically, the flow control assembly 44 includes one or more flow restricting structures to restrict the volume of flow through the screen 16. The flow control assembly 44 is typically located in the flow path between the filter portion and the interior of the base pipe.

As illustrated in FIG. 3 a, the flow-control assembly 44 uses helix channel flow paths to restrict flow. The length, cross section and other characteristics of the paths may be selected to thereby vary the fluid flow volume through the screen. Although the helix path flow-control type screen assembly is illustrated herein, it will be appreciated that other configurations of screens and flow-control devices are possible in keeping with the principles of the inventions. Persons of skill in the art will appreciate that other flow-control assembly designs could be used, such as those disclosed in U.S. patent application Ser. No. 11/409,734 entitled INFLOW CONTROL DEVICES FOR SAND CONTROL SCREENS to William Richards, et al., filed on Apr. 24, 2006, which application is incorporated herein by reference for all purposes.

FIGS. 4, 5 a and 5 b illustrate respectively, an isomeric view and cross-section views of a cylindrical structure that can comprising one embodiment of either the drainage layer 36 or one embodiment of the filter 32. By referring to FIGS. 4, 5 a and 5 b the structure and method of making the drainage layer 36 of FIG. 2 will be described as an example. In this embodiment, the drainage layer 36 is a tubular member with a generally cylindrical shape.

The wall of the drainage layer 36 is a “wire wrapped rib based structure”, i.e., the wall comprises a plurality of ribs 46 each joined to wraps 50 of a wire 48 positioned in spiral pattern. In the illustrated embodiment the ribs 46 have a generally tapered cross-section. In the drainage layer embodiment, the wire 48 is of no particular cross section shape but can have special shapes such as is the “V” and trapezoidal cross sectional shaped wire used in what are know in the industry as wire-wrapped screens. The wraps 50 are spaced apart to form gaps 52 and welded to the ribs 46 to form a self-supporting cylindrical screen-like structure. In the drainage layer embodiment the gaps 52 are selected to be of a size to allow fluid flow between the individual wraps 50. In an alternative embodiment of FIG. 5 a, the ribs 46 are located outside the wire 48. As is known by persons of skill in the industry, the wire 48 is made from a material that is rigid enough to remain in place but sufficiently ductile to deform to a shape to contacts the ribs 46. The wire 48 is typically metallic material and in the illustrated embodiment it comprises steel material that is welded to the ribs 46.

The drainage layer 36 is positioned in the annular space between the filter and the base pipe. The drainage layers form supports for the filter and a fluid flow paths in the annulus surrounding the base pipe. The wall of the drainage layer forms or includes axial and radial fluid flow paths therein to allow fluid flowing through the filter to flow along the base pipe.

The drainage layer 36 can be left in a generally tubular shape or can have a longitudinally extending cut 54 severing the wire wraps 50 and forming a gap 39 between the severed edges. The cut extends the length of the screen thereof. Ribs 56 extend along the edges of the cut 54 to anchor the free ends of the wire wraps 50. In the illustrated embodiment, the cut 54 is parallel the axis of the layer 36, or generally transverse to the wraps. It is envisioned that the cut could extend longitudinally along the drainage layer 36, but not parallel to the center line, for example, to extend in a curve or spiral.

The drainage layer 36 could be formed by positioning the ribs 46 and 56 on a cylindrical mandrel or other form and the wire 48 positioned around and welded to the ribs in a conventional manner as used to make wire screens. The wires can be positioned to form a generally cylindrical shape which is some what distorted into polygonal flats (not shown) in the portions spanning the unsupported space between adjacent ribs. The inner-most surfaces of the ribs (or, in FIG. 5 a, the inner surface of the wraps 50) define an inner-base cylinder shape and the outer surfaces of wraps 50 (or, in FIG. 5 a, the outer surface of the ribs) define an outer-base cylinder shape. The inner-base cylinder shape faces the outer surface of the base pipe 30, and the outer-base cylindrical faces the interior surface of the filter 32.

The cut 54 can be formed either before or after removal of the drainage layer 36 from the mandrel. The cut 54 could be formed as a narrow slit, or a section could be removed to form a wider gap. Once cut, the drainage layer 36 could be described as having a generally has a closed “C” shaped cross section.

The drainage layer 36 is installed on a base pipe 30 by spreading the cut 54 as necessary preferably without substantial permanent deformation and inserting the base pipe 30 in the center opening. It is envisioned that the drainage layer 36 could be dimensioned so that the inner-base cylinder shape is smaller than the outside surface of the base pipe 30. When the drainage layer 36 is constructed from wire 48 made from most metallic materials, the assembly will have spring-like characteristics to grip the base pipe and hold the drainage layer in place adjacent the base pipe 30.

By forming the drainage layer separately from the base pipe, the drainage layer can be positioned tightly surrounding in a snug or interference fit but need not be coupled (joined) to the base pipe itself. However, the drainage layer could be formed as described herein and if desired welded or otherwise joined to the base pipe after positioning on the base pipe.

Alternatively, the drainage layer 36 may be dimensioned so that the outer-base cylinder shape is larger than the interior shape of the filter 32. For example layer 36 could have a larger outer diameter than the internal diameter of the filter 32. The outer shape of drainage layer can be compressed while it is inserted into the filter, then released to contact or lay adjacent to the filter's inner surface in a snug or interference fit. The embodiment of FIG. 5 a with the ribs on the outer surface is ideal for this alternative configuration.

In FIG. 5, the cut 54 is held spread open by a channel shape clip 58 wedged against the ribs 56. Preferably, the cut 54 is spread to enlarge the inner-base cylinder to a sufficient size to allow the drainage layer 36 to be positioned around the base pipe 30. If the drainage layer 36 is left tubular, it can be formed using the base pipe 30 as a mandrel or installed on the base pipe 30 by inserting the base pipe 30 through the center of the drainage layer 36. The filter and shroud can be installed to complete assembly of the well screen.

As previously stated, an embodiment of the filter 32 could be constructed as illustrated and described in FIGS. 4, 5 a and 5 b with regard to the drainage layer 36. These FIGS. 4, 5 a and 5 b will be used to describe this embodiment of the filter 32 and for purposes of description, reference numerals used in the describing this filter 32 embodiment are the same as previously used to refer to like parts of the drainage layer 36. In this filter embodiment, the gaps 52 (spaces between the wrap wires) are selected to be small enough to perform filtering of solids from the fluids passing through the filter 32. The wire 48 positioned around the ribs 46 of the filter 32, preferably has a tapered V or trapezoidal cross section shape but need not be of any special shape. As with the drainage layer the filter can be cut end to end to form for installation and the cut can be closed after installation, as described with respect to the drainage layer.

A well screen can be assembled using this embodiment of the filter 32 cut end to end. The filter 32 can appropriately dimensioned spread open and assembled in a snug or interfering fit around any of the embodiments of the drainage layer or alternatively around the base pipe itself. Indeed, in one embodiment the filter 32 is installed around a base pipe having a wire wrapped drainage layer structure thereon. After assembly but before installing the shroud 34, the cut 54 in the filter could be closed as described with respect to the drainage layer.

In an alternative well screen embodiment, the filter 32 is installed inside the shroud 34 by first compressing the filter 32 and then releasing it to expand after positioning it inside the shroud 34. The cut 54 can be closed if desired, and the base pipe installed inside the filter.

FIGS. 6 and 6 a illustrate an alternative exemplary embodiment of the drainage layer 60 located between the base pipe 30 and filter 32. Drainage layer 60 comprises a plurality of tubular members 62 extending along the length of the filter 32. The ends of the tubular members 62 have one end blocked off and the other end in fluid communication with the intake manifold 42 of the flow control device. The tubular members 62 have their walls perforated as shown in FIG. 6 a. Holes 64 or slots 66 of various sizes and shapes are suitable to act as perforations. The tubes 62 are illustrated as joined together at their edges. A generally “C” shaped cross-section structure is formed by connecting adjacent tubes 62 and leaving one opening to form a gap 68. The gap opens up during installation on the base pipe 30. Alternatively, unconnected tubes could be arranged around the base pipe and either left unattached or held in place on the base pipe by fasteners, bands, welding or the like.

FIG. 7 illustrates an alternative exemplary embodiment of the drainage layer 70 located between the base pipe 30 and filter 32. Drainage layer 70 comprises a sintered laminate wire tube. Alternatively, the tube can be slit along its length as previously described. Multiple layers of woven wire mesh may be laminated together using sintering (molecular diffusion-bonding process). In this embodiment, the same process used to fuse individual wires together within the layers of wire mesh is used to join adjacent layers of mesh. The wire mesh laminates can range from a two-layer laminate of fine filter meshes with an overall thickness of 0.006″ to heavy plate-like or brick-like structures comprising many hundreds of layers of various meshes with overall thicknesses of 2″ or more. By combining multiple layers of different mesh weaves, it is possible to design materials with specific thicknesses, permeability, pore size and mechanical strength.

FIGS. 8, 8 a, and 8 b illustrate an alternative exemplary embodiment of the drainage layer 80 located between the base pipe 30 and filter 32. Layer 80 comprises a plurality of “U” shaped elongated channels 82 joined together at 84 to form a tube structure. Alternatively, the tube can form a slit along its length as previously described. The channels 82 can have slots (see FIG. 8 a) and/or can have perforations (see FIG. 8 b) to permit cross flow between the passageways formed by the channels.

FIG. 9 illustrates an alternative exemplary embodiment for a drainage layer 90 located between the base pipe 30 and filter 32. In this embodiment, the elongated channels 92 can be described as having a generally “S” or “Z” shape, and adjacent channels are joined together at 94 to form a tube. Alternatively, the tube can form a slit along its length as previously described. Holes 96 (and/or slots not shown) are provided in channels 92 to permit cross flow between the passageways formed by the channels.

FIGS. 10 and 10 a illustrate an alternative exemplary embodiment of the drainage layer 100 located between the base pipe 30 and filter 32. The drainage layer is constructed out of sheet material 102 formed into a corrugated shaped tubular member in which the surface of the sheet material has been deformed to form flow paths. Alternatively, the tube can be slit along its length as previously described. Holes 104 (and/or slots not shown) are provided in sheet metal 102 to permit cross flow between the passageways formed by the channels.

FIGS. 11 and 11 a illustrate an alternative exemplary embodiment of the drainage layer 110 located between the base pipe 30 and filter 32. Layer 110 comprises either a sheet of material with its wall formed into a tubular member 112 with “V” shaped deformation in the wall thereof forming flow paths. Alternatively a plurality of elongated “V” shaped members 114 on the outside of the base pipe 30 could be used. The members 114 can be joined together at their adjacent edges to form a tube or mounted individually on the base pipe 30. Alternatively, the tube can have a slit along its length as previously described. Holes 116 and/or slots 118 are provided in the members 114 or the tube 112 to permit cross flow between the corrugations and flow passageways formed by the members.

The drainage layer could also be formed from sheet material that is a generally cylindrical shaped tubular member and wherein the wall is deformed to form a plurality of indentions and protrusions in the surfaces of the material. These deformations form flow paths when installed on a base pipe.

FIG. 12 illustrates an alternative exemplary embodiment of the drainage layer 120 located between the base pipe 30 and filter 32. Layer 120 is formed by packing the annular area formed between the filter 32 and base pipe 30 with particulate material 122 such as proppant-type materials used in fracturing treatments and in gravel packing installations. Particulates, such as sand, gravel, ceramic, metal and plastic proppants and gravel pack materials could be used. While a variety of sizes could be used, particulates sized from 0.02 inches to 0.264 inches are preferred.

FIG. 13 illustrates an alternative exemplary embodiment of the drainage layer 130 located between the base pipe 30 and filter 32. In this example, drainage layer 130 comprises a tube 132 formed at least in part from a ceramic filter material. Ceramic filter material is commercially available from a plurality of suppliers, such as, Cleen-Flo Alumina Ceramic Foam Filters; Cleen-Flo Silicon Carbide Ceramic Foam Filters; and Cleen-Flo Zirconia Ceramic Foam Filters from Blasch Precision Ceramic of Albany, N.Y. Material with at least about 50% porosity is preferred. As previously discussed, the tube 130 could be cut in a longitudinal direction from end to end. In addition, the drainage layer 130 could be formed from longitudinally-extending members with a variety cross-section shapes, such as, quadrilaterals, triangles, circular, oval, tubular or others.

FIG. 14 illustrates an alternative exemplary embodiment wherein multiple screen assemblies 200 a and 200 b are mounted on a single base pipe 202. For purposes of illustration only two assemblies are illustrated, however it is to be understood that more than two could be mounted on a single base pipe. Each screen assembly comprises a filter 204 and outer perforated shroud 206. A drainage layer 210 is located in the annular space 212 formed between the outer surface of the base pipe 202 and inside surface of the filter 204. Although the drainage layer 210 is illustrated as being formed with longitudinally extending ribs 214 with wire 216 wound around the exterior thereof, it is anticipated that the screen assemblies 200 a and 200 b and their base pipe, filter, shroud and drainage layer components could be constructed as described with respect to any of the FIGS. 1-13 embodiments. In addition, assembly of the drainage layer 210 on the base pipe 202 could be performed according to the methods disclosed hereinabove. End housings 218 and interior housing 220 support the screen assemblies 200 a and 200 b on the base pipe and contain flow passages 222 connecting the screen assemblies, their drainage layers and any flow control devices on the base pipe.

Three separate axially spaced interconnected flow control devices are illustrated in the FIG. 14 embodiment. On the left hand side, an orifice type inflow control 230 is illustrated. This inflow control could be in the form of any of the devices illustrated or described elsewhere herein. Illustrated in the center between the two screen assemblies is a check valve assembly 240. Illustrate on the right hand side is a sliding sleeve 250 movable to selectively open or close one or more ports 252 in the base pipe wall. Three different axially spaced flow control devices have been illustrated in FIG. 14 in a two filter assembly on a single base pipe simply for purposes of explanation. It is envisioned that: (1) more that two filter assemblies could be present on a single base pipe, (2) more or less flow control devices could be present as needed, (3) other types of flow control devices could be present, and (4) other combinations of the same or different flow control devices are anticipated.

When installed in a wellbore the base pipe 202 is in fluid connection to the production string. Hydrocarbon fluid production flow from the material surrounding the wellbore enters the assembly by perforations in the shrouds 206. The fluid then flow through the filter 204 where particles are removed (filtered out) and into the drainage layer 210. Flow in the drainage layer 210 (in each of the disclosed embodiments) can move radially and axially along the outer surface of the base pipe. The hydrocarbon flow exits the drainage layer 210 and enters the flow passages in the end and interior housings 218 and 220, respectively. In this manner each of the screen assemblies 200 a and 200 b and the flow control devices 230, 240 and 250 located in the housings are in fluid communication with each other.

In the FIG. 14 embodiment, flow enters the base pipe through the inflow control orifice 230 and the uncovered port 252 of the sliding sleeve 250. To regulate flow sleeve 250 can be moved by wire line to selectively open or block port 252. If treatment fluid need be pumped from the string into the materials surrounding the filter assembly the larger sized port of check valve 240 will be opened allowing fluids to flow into the housing 220 and thought the screen assemblies 200 a and 200 b.

The drainage layer embodiments described and illustrated herein provide support for the filter and allow fluids flowing through the filter to flow radially and longitudinally along the surface of the base pipe. While FIGS. 2, 3 and 14 illustrate well screens with flow control devices, it is to be understood that the various embodiments of filters and drainage layers have application in well screens without flow control device and wherein the base pipe has numerous openings in the wall thereof.

Therefore, the present inventions are well adapted to carry out the objects and attain the ends and advantages mentioned as well as those which are inherent therein. While the inventions have been depicted, described, and are defined by reference to exemplary embodiments of the inventions, such a reference does not imply a limitation on the inventions, and no such limitation is to be inferred. The inventions are capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts and having the benefit of this disclosure. The depicted and described embodiments of the inventions are exemplary only, and are not exhaustive of the scope of the inventions. Consequently, the inventions are intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects. 

1. A well screen comprising: a first tubular member having a longitudinal axis and an exterior surface; a filter surrounding the exterior surface of the tubular member and forming an annular space between the filter and tubular member; and a second tubular member positioned in the annular space formed between the filter and first tubular member; the second tubular member having a wall with a cut therethrough extending substantially from one end of the second tubular member to the other end thereof, and wherein the second tubular member provides fluid flow paths permitting flow in a longitudinal direction along the first tubular member.
 2. The well screen of claim 1, wherein the second tubular member comprises a wire-wrapped structure having a plurality of longitudinally extending rods arranged parallel to the outer surface of the first tubular member and having wire wrapped around the rods.
 3. The well screen of claim 2, wherein the wall of the wire-wrapped structure additionally comprises an outer diameter larger than the internal diameter of the filter, and, after cutting, is positioned in the annular space by radially compressing the wire-wrapped structure before inserting the screen inside the filter.
 4. The well screen of claim 2, wherein the wall of the wire-wrapped structure additionally comprises an inner diameter less than the outside diameter of the first tubular member, and, after cutting, the wire-wrapped structure is slid onto the first tubular member.
 5. The well screen of claim 1, wherein the second tubular member comprises a wall made from sheet material.
 6. The well screen of claim 5, wherein the sheet material additionally comprises deformations forming flow paths in the annular space.
 7. The well screen of claim 6 wherein the sheet material additionally comprises openings in the wall of the sheet material.
 8. The well screen of claim 1, wherein the second tubular member additionally comprises a wall formed from a plurality of layers of mesh filter material.
 9. The well screen of claim 1 wherein the second tubular member additionally comprises a wall formed from a plurality of channel-shaped members, the channel-shaped members extending in a longitudinal direction along the surface of the first tubular member.
 10. The well screen of claim 9 wherein the channel members additionally comprise perforations in the wall of the channel members.
 11. The well screen of claim 1 wherein the second tubular member has a wall formed from a plurality of tubular members, the tubular members extending in a longitudinal direction along the surface of the first tubular member.
 12. The well screen of claim 10 wherein the tubular members additionally comprise perforations in the walls of the tubular members.
 13. The well screen of claim 1 wherein the second tubular member comprises particulate material.
 14. The well screen of claim 13, wherein particulate material is selected from the group consisting of proppants and gravel pack materials.
 15. The well screen of claim 1 wherein the second tubular member additionally comprises a wall formed from ceramic filter material.
 16. The well screen of claim 15 wherein the ceramic filter material additionally comprises a wall with a 50% porosity.
 17. The well screen of claim 1 wherein the first tubular member and the second tubular member being positioned juxtaposed by an interference fit between the two structures.
 18. A well screen comprising: a base pipe having a longitudinal axis and an exterior surface and at least one perforation in the wall of the base pipe; a filter surrounding the exterior surface of the base pipe and forming an annular space between the filter and the base pipe; and a generally tubular drainage layer member positioned in the annular space formed between the filter and the base pipe; the wall of the drainage layer comprising sheet material.
 19. The well screen of claim 18 wherein the sheet material additionally comprises deformations in the sheet material to form flow paths in the annular space.
 20. The well screen of claim 19 wherein the sheet material additionally comprises perforations in the sheet material.
 21. A well screen comprising: a base pipe having a longitudinal axis and an exterior surface and at least one perforation in the wall of the base pipe; a filter surrounding the exterior surface of the base pipe and forming an annular space between the filter and base pipe; and a generally tubular drainage layer member positioned in the annular space formed between the filter and the base pipe; the wall of the drainage layer formed from a plurality of channel-shaped members, the channel-shaped members extending in a longitudinal direction along the surface of the first tubular member.
 22. The well screen of claim 21 wherein the channel members additionally comprise perforations in the channel members.
 23. A well screen comprising: a base pipe having a longitudinal axis and an exterior surface and at least one perforation in the wall of the base pipe; a filter surrounding the exterior surface of the base pipe and forming an annular space between the filter and tubular member; and a generally tubular drainage layer member positioned in the annular space formed between the filter and the base pipe; the wall of the drainage layer comprising a plurality of tubular members, the tubular members extending in a longitudinal direction along the surface of the first tubular member.
 24. The well screen of claim 10 wherein the tubular members additionally comprise walls that are perforated.
 25. A well screen comprising: a base pipe having a longitudinal axis and an exterior surface and at least one perforation in the wall of the base pipe; a filter surrounding the exterior surface of the base pipe and forming an annular space between the filter and tubular member; and a generally tubular drainage layer member positioned in the annular space formed between the filter and base pipe; the drainage layer comprising particulate material.
 26. A well screen comprising: a base pipe having a longitudinal axis and an exterior surface and at least one perforation in the wall of the base pipe; a filter surrounding the exterior surface of the base pipe and forming an annular space between the filter and tubular member; and a generally tubular drainage layer member positioned in the annular space formed between the filter and the base pipe; the wall of the drainage layer comprising ceramic filter material.
 27. The well screen of claim 26 wherein the ceramic filter material comprises material with a 50% porosity.
 28. A screen for placement at a subterranean location in a wellbore for removing solids from fluids entering the wellbore, the screen comprising: a unitary base pipe having an internal passageway, a longitudinal axis and an exterior surface and at least one flow path through the wall of the base pipe providing fluid communication between the exterior of the base pipe and internal passageway of the base pipe; a plurality of axially-spaced annular filters surrounding the exterior surface of the base pipe, each of the filters located in the path of fluid flow between the wellbore and the interior passageway of the base pipe and each filter forming an annular space between the interior of the filter and the exterior of the base pipe; drainage layer members positioned in each of the annular spaces formed between each filter and the base pipe; each drainage layer providing fluid flow paths permitting flow in a longitudinal direction along the exterior surface of the base pipe, the wall of each of the drainage layers comprising a wire-wrapped structure having a plurality of longitudinally extending rods arranged parallel to the outer surface of the first tubular member and wire wrapped around the rods, and an annular structure on the base pipe having at least one passageway providing fluid communication between each drainage layer and at least one flow path through the wall of the base pipe whereby fluid flowing through the filter from the wellbore flows through the drainage layer and at least one flow path through the wall of the base pipe and into the interior passageway in the base pipe.
 29. The well screen of claim 28 wherein each of the drainage layer structures comprises a wall with a cut therethrough extending substantially from one end of the drainage layer structure to the other end thereof.
 30. The well screen of claim 28, wherein the wire-wrapped structure additionally comprises the wall of each of the wire-wrapped structures has an outer diameter larger than the internal diameter of the filter, and, after cutting, is positioned in the annular space by radially compressing the wire-wrapped structure before inserting the screen inside the filter.
 31. The well screen of claim 28, wherein the wire-wrapped structure additionally comprises the wall of each of the wire-wrapped structure has an inner diameter less than the outside diameter of the first tubular member, and, after cutting, the wire-wrapped structure is slid onto the first tubular member.
 32. The well screen of claim 28 additionally comprising at least one flow control device located in the flow path of fluid flowing from the filter to the interior of the base pipe.
 33. The well screen of claim 28 additionally comprising a plurality of parallel flow paths through the wall of the base pipe and fluid flow control devices located in at least two of the parallel flow paths.
 34. A downhole apparatus comprising: a single segment of perforated base pipe; a plurality of segments of filtering media arranged in a longitudinally spaced-apart relationship along the base pipe, and disposed externally to and in a spaced-apart relationship with the base pipe thereby defining an annular space betweeen the interior of each filtering media and the exterior of the base pipe; and, a plurality of flow control devices disposed on the segment of base pipe and located in the spaces between the segments of filtering media.
 35. The apparatus of claim 34 additionally comprising a drainage layer located in the annular space and permitting longitudinal fluid flow.
 36. The downhole apparatus of claim 35, wherein a cut extends substantially from one end of the drainage layer to the other end of the structure.
 37. The downhole apparatus of claim 35 wherein the drainage member is a wire wrap screen.
 38. The downhole apparatus of claim 37 wherein the wire wrap screen is rib based.
 39. A well screen comprising: a first tubular member; a generally tubular shaped fluid filter having a longitudinally extending wall, the filter positioned with the first tubular member extending into the filter, the filter having a wall comprising a plurality of longitudinally extending rods and having wire connected to and wrapped around the rods; and a cut through the wall extending the longitudinal length of the filter.
 40. The apparatus of claim 39 additionally comprising an annular space between the filter and the first tubular member and a drainage layer located in the annular space.
 41. The well screen of claim 40 additionally comprising a drainage layer that permits longitudinal fluid flow.
 42. The well screen of claim 40 wherein the drainage member comprises a second wire wrapped structure.
 43. The well screen of claim 41 wherein the second wire wrap structure additionally comprises a plurality of longitudinally extending rods.
 44. The well screen of claim 39 wherein the wire has a V shaped cross section.
 45. The well screen of claim 39 wherein the wire has a trapezoidal cross section shape.
 46. The downhole apparatus of claim 4 wherein the first tubular member has a wall with at least one opening therein for permitting fluid flow from the exterior to the interior thereof.
 47. A method of assembling a downhole apparatus comprising: selecting a segment of perforated base pipe; selecting a plurality of segments of filtering media; positioning the segments of filtering media in a longitudinally spaced-apart relationship along the segment of base pipe; and, positioning a flow control device in one or more of the spaces between segments of filtering media. 